Radio telephone installation with secure prepayment service.

摘要

During the intercommunication between the base station and the stand-alone set, the first authentication means (MA1) generate first of all a keyword (MCL) depending on the tariff (CONS) in force for using the service, and transmit the keyword to the stand-alone set. The second authentication means (MA2) next calculate the transform (SRES) of the said keyword (MCL) under the cryptographic function F with the aid of the subscriber's secret key (KEY) and transmit the said transform (SRES) to the first authentication means (MA1) which finally check the authenticity of the said transform (SRES) in order to totally inhibit the intercommunication should the authenticity not be confirmed by the said check. ……